activation on volume lic. media

I am very confused about the activation on volume lic. media of Vista.
Hope someone can help me out.

I read many documents about Vista activation and they all said Vista
installation requires activation for volume license media. But when I
talked to the Microsoft customer service department (both technical and
licensing), some of them said activation is not required for Volume lic.
media. I was confused.

The reason I want to find out this information is that I would like to
know what would happen if I restore a Vista image (created from a volume
license media)on a PC which has its copy of oem Vista activated.
Microsoft allows reimaging of operating system using volume licensing
media. This works for XP volume licensing media because it doesn't
require activation. But if Vista volume license media require
activation, does that mean I need to purchase a volume license for this
"new installation".

Thanks